A windshield, or windscreen, is a front facing window which protects the driver and other vehicle occupants from wind, flying debris, and inclement weather. While providing protection, windshields tend to accumulate dirt and other substances, such as road salt, which, because they obscure vision and tend to stick to the windshield, need to be washed off.
A typical windshield wiper consists of a rubber wiper blade attached to a wiper arm which pivots so as to cause the rubber blade to wipe water, snow, etc. from the surface of the windshield. Other types of windshield debris, particularly dry materials, require a washer fluid delivery system for their removal, wherein the washer fluid serves as a softening solvent for this material.
A conventional washer fluid delivery system consists of a reservoir, a pumping mechanism and a nozzle. The nozzle is configured to provide a uniform spray of fluid over critical debris removal areas of the windshield. The fluid is sprayed onto the windshield, and the wiper system is operated so as to remove dirt, salt, and other debris from the windshield. The nozzle is designed to optimize performance in such a fashion as to minimize the amount of wiping required to clear the windshield of debris.
Turning now to the Drawings, FIGS. 1 through 3 depict a conventional motor vehicle windshield, conventional windshield wipers and a conventional prior art windshield washer fluid delivery system used in association therewith.
FIG. 1 shows a windshield 10 and, abutting thereto, a pair of windshield wipers 12, each including a rubber wiper blade 14 attached to a reciprocally movable wiper arm 14′, wherein the windshield wipers are configured to facilitate removal of precipitation falling or splashed onto on the windshield, whereby the driver is provided a clear view of the road despite inclement weather. The windshield 10 has disposed in adjacency thereto a pair of spray heads 16 (one spray head for each windshield wiper), each spray head has a nozzle body which has disposed therein a nozzle which emits at a nozzle orifice thereof a wide spray pattern 18 onto the surface of the windshield 10. Similarly to FIG. 1, FIG. 2 depicts the windshield 10 and windshield wipers 12 including the wiper blades 14 and wiper arms 16, wherein now the nozzle body 16′ of each spray head has disposed therein a nozzle which emits at its nozzle orifice a narrow spray pattern 18′ onto the surface of the windshield 10.
FIG. 3 is a diagram of a conventional prior art windshield washer fluid delivery system 40. The driver of the motor vehicle activates a switch 20 which produces a demand for windshield washer fluid at a conventional washer fluid control module 22 via data line 24. The washer fluid control module actuates a washer fluid pump 28 via data line 26. Washer fluid 30 is then drawn from a washer fluid reservoir 32 through a washer fluid supply line 34 to the washer fluid pump and thereupon pressured out through a washer fluid supply delivery line 36. The washer fluid delivery line 36 is connected to both of the spray heads 16 through the nozzle body thereof to a wide spray pattern nozzle 38 (in the operative case of FIG. 1). The pressurized washer fluid then passes out through a wide spray pattern nozzle orifice 38′ of the wide spray pattern nozzle, whereupon the emitted wide spray pattern 18 is directed to the windshield as shown at FIG. 1.
Spray nozzle technology is notoriously well known in the art. Generally speaking, the configuration of the nozzle orifice dictates the nature of the spray pattern produced by the nozzle, wherein the nozzle orifice utilizes the kinetic energy of a pressurized liquid moving through the nozzle to break the liquid up into an airborne spray consisting of collection of moving droplets due to the pressure drop upon exit of the nozzle orifice. The size and shape of the nozzle orifice determines how broadly dispersed the droplets will be upon exit from the nozzle orifice, thereby effecting specification of the width of the spray pattern the nozzle produces. For example, a cylindrically-shaped nozzle orifice opening may provide a narrow spray pattern, while a V-notch shaped nozzle orifice opening may provide a wide spray pattern.
In general, a spray can be envisioned as a collection of liquid droplets moving through air, having both speed and momentum which are influenced by the relative movement of the air. The trajectory of the collection of droplets constituting the spray may be predictable and moderately influenced by the air when the air has laminar flow and is relatively slow moving, as for example when a motor vehicle is traveling at slower speeds. However, the trajectory of the collection of droplets constituting the spray can be unpredictable and greatly influenced when the air is buffeting and is relatively fast moving, as for example when a motor vehicle is moving at higher speeds. Accordingly, when a motor vehicle is moving at relatively high speed, the washer fluid spray can be erratic, missing the intended target location of the windshield, even loosing a quantity of the spray to the air itself, never even reaching the windshield. This phenomenon of vehicle speed and windshield washer speed is exacerbated for wide spray patterns. Problematically, a narrow spray pattern (as for example shown at FIG. 2), although less susceptible to the vagaries of wind interaction, has the disadvantage that a lesser area of the windshield will be exposed to the spray.
Accordingly, what remains needed in the art is to somehow provide selection of washer fluid spray pattern width based upon either or both of an autonomous selection and a driver selection, so as to thereby provide an optimal spray pattern adapted for best wetting of the windshield under varying environmental conditions.